Medical devices are commonly used to access remote regions of the body to deliver diagnostic or therapeutic agents to those regions and to perform surgical procedures on those regions. For example, endoscopes may use body airways and canals to access the colon, esophagus, stomach, urethra, bladder, ureter, kidneys, lungs, bronchi, uterus, and other organs. Catheters may use the circulatory system as pathways to access treatment sites near the heart or may use the urinary canal to access urinary regions.
Medical devices are often introduced into the body through a large artery such as those found in the groin or in the neck. The devices are often passed through ever-narrower arteries until they can reach the operative site inside the body. Many such pathways may curve, loop around, and even wind back. In order to navigate the medical device through the pathways to the operative site, the medical device must be flexible to allowing bending, yet have enough column strength to prevent buckling of the medical device as it is pushed. Pull wires incorporated into the medical device can be used to articulate a distal end of the device.